I've noticed exactly the same thing. Report a sub 50 feedback member for keyword spamming and the listings are gone within hours, report a 500+ feedback member and the listings are never, and I mean NEVER removed or amended. As much as I don't buy into conspiracy theories it is extremely obvious that not all sellers are created equal in eBay's eyes. It's their playground of course and they are free to do as they wish within the appropriate legal confines but it doesn't sit well with me.

Same thing happens when you report a seller who is refusing Paypal, if it's a small fish then they are gone but with the bigger sellers it seems as though they think 7% of something is better than 7% + 2.4% of nothing, regardless of advertised policy.